EXTRACT DATA BETWEEN STRINGS OR TAGS

Question

I AM FAIRLY NEW TO USING PHP COMMANDS AND REGEX. i have a html document retrieved through php commands , now i want to extract the data from html between two strings . for example,

**<h4 class=3D"style1"> HIGH (blah)</h4>**
<h4><br>
<br></b>
 <br>
&nbsp;</h4>
<TR>
 <TD width=3D"513">
<B**>**textttttttttt**</**B><br><br><br><br><hr><table><tr><td>=
<b>texttttt<br><br><br><br>textttttttt<table>ttttttttttttt</table>ttttttttttttt
</table></td></tr></table> 
<TD width=3D"513">
<ul>
= 
=
</u1>                              
**<p align=3D"right"><b>REGISTRAR(EVALUATION)<=
/b></p>**

i need the text between the strings "HIGH" and "REGISTRAR".mainly, i needed the data from the tags and ,but there are many instances where this tag occurs.

ANY SUGGESTIONS ARE REQUESTED FROM U ARE THANKFUL.THANKS IN ADVANCE